Printing module for high speed printers



May 26, 1970 G. PONZANO 3,

PRINTING MODULE FOR HIGH SPEED PRINTERS Filed Sept. 50. 1966 INVENTOR.

I B lanvfugl Ponzznow United States Patent O US. Cl. 101-93 4 Claims ABSTRACT OF THE DISCLOSURE A high speed print hammer module including an electromagnet, an arm supporting the armature and hammer, which are at opposite ends of the arm, a pivot point intermediate the extremities of the arm, and a deformation in the arm between the armature and pivot point.

A rewritten specification is submitted herewith for substitution in place of the specification as originally filed. The rewritten specification parallels the specification as initially filed and the amendments hereinafter referred to should be made with respect to this rewritten specification. This practice is being followed to permit ease of examination of the specification to verify that no new matter has been added.

The invention relates to a modular printing unit including a number of print hammers, a corresponding number of actuating electromagnets, other devices intended for the operation of the same, and a frame carrying said members and devices.

The invention is adapted for use in a high speed printer of the type substantially comprising a continuous rotating typewheel, wherein the characters are disposed in adjacent columns disposed in circular rings, a set of print hammers, for example one for each column, actuated by a set of electromagnets, a continuous paper sheet for receiving print thereon and a carbon paper or an inked ribbon interposed between the typewheel and the hammer set, said hammers being so disposed, that, when an electromagnet is energized, the hammer drives both the print receiving paper and the carbon paper against the rapidly rotating typewheel, in a manner as to print a particular character which at that moment is in the correct printing position of the column corresponding to the actuated hammer on the print receiving paper.

In order to obtain a high printing speed and neat and perfectly aligned print, it is necessary that the forward and backward motion of the print hammer be very rapid, and subject to a well defined motion and not aflected by vibrations and rebounds.

Moreover, as a print hammer corresponds to each column and the distance between columns is equal to the pitch of printing, that is, to the distance between two consecutive printed characters, it is inecessary to take precautions so that the distance between two print hammers is equal to said pitch, notwithstanding that the transverse dimension of the electromagnets is most often greater than said pitch.

What has been said also applies to a device in which the characters are carried by chains or other linearly movable members and, in general to any disposition through which the printing is obtained by driving the paper against a set of characters in rapid motion by means of a hammer.

An object of the present invention is to allow a rational arrangement of the electromagnets and of the hammers to be actuated thereby, and a grouping of said members in modular units, each one of said modular units compris- 3,513,773 Patented May 26, 1970 ing, for instance, four such electromagnets and four such hammers. Such modular units, which will be hereafter referred to as print modules made according to the invention, may be easily and separately disassembled from their common support, that is, it is possible to remove any one of them without operating on the adjacent ones.

Another object of the invention is to ensure, by means of a particular form of said printing hammers, the right measure of elasticity and the proper concentration of the elastic deformation of said hammers, in order to obtain a rapid and correct forward and backward motion, without rebounds or vibration, thus obtaining a neat print, perfect alignment and the absence of smear.

The aforesaid objects are attained, according to the invention, by a particular forming of the hammers, as is explained in the following disclosure.

The invention may apply to print modules wherein the number of hammers and electromagnets differs from four, as for example, two, six, eight or any other even number.

These and other features of the invention will become apparent from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings in which:

FIG. 1 represents a sectional view of the print module, wherein the members and devices not relevant to the present invention are not shown.

FIG. 2 is a plan view of the module of FIG. 1.

FIGS. 3a and 3b each represent a view of one of the two types of print hammers included in a module.

FIGS. 4a and 4b each represent a view of the other type of print hammers included in the same module.

With reference to FIGS. 1 and 2 the print module comprises four print hammers 1, 2, 3, 4 (FIG. 2) and four corresponding electromagnets 10, 11, 12 and 13.

The four hammers are pivoted on a fixed axle 5 and are free to accomplish a small rotative motion around it.

Each one of the said hammers comprises, on one side of the rotation axis, an extension arm 16 (FIG. 1) which terminates in a print head 17 provided to drive the paper against the typewheel. On the opposite side of the rotation axis, each hammer comprises a second arm which carries an armature (6, 7, 8, 9 in FIG. 2), consisting of a magnetizable material such as iron sheets.

The axial planes of the extension arms and of the print heads, as appears from FIG. 2, are spaced apart a distance equal to twice the printing pitch, and leave between the print heads the space necessary to permit the interleaving of other print heads pertaining to another print module placed on the opposite side of the print line, according to a known disposition.

The hammers 1 and 3, representedin FIGS. 3a and 311 both have the same shape, and the armature carrying arm appears, when observed in a direction parallel to the axis of rotation, as in FIG. 3a, substantially aligned with the extension arm carrying the print head 17. Hammers 2 and 4, represented in FIGS. 4a and 4b, also both have the same shape, but the armature carrying arm is, when observed in the said direction, as in FIG. 4a, substantially at a right angle with the extension arm 19 carrying the print head 20.

The four armatures 6, 7, 8, 9 (FIG. 2) formed by an assembly of magnetic sheets, are subject to attraction by the corresponding electromagnets 10, 11, 12 and 13 when these respective electromagnets are energized. As a consequence of the diiference in shape of hammers 1 and 3 from that of hammers 2 and 4, the electromagnets 10 and 12 are opportunely disposed in a different manner than electromagnets 11 and 13, as may be seen in FIGS. 1 and 2. As a consequence, two adjacent electromagnets may be so located, that their axial symmetry planes may be 3 spaced apart a quantity smaller than their transverse dimension.

Considering electromagnet 10, armature 6 and 'hammer 1, it may be seen that when electromagnet 10 is energized, armature 6 is attracted thereto and hammer 1 rotates about the axle so that the head 17 is brought against the rotating typewheel against the action of the restoring spring 18.

The motion of the armature 6 terminates when it comes into contact with the polar pieces of electromagnet 10. According to the invention, this contact takes place before the head 17 terminates its stroke, the remainder of the stroke being accomplished by elastic deformation of the arm carrying the hammer and armature.

Therefore, a quantity of elastic energy is stored in the hammer, and this elastic energy is effective in cooperation with the restoring spring 18, When the stroke is terminated in forcibly and rapidly returning the head 17, thus carrying the hammer back to its rest position.

As may be seen from FIG. 2, if electromagnet 10, 00- d operating with hammer 1, were located in such a manner, as to have its axial plane coincident with the axial plane of the hammer, it would necessarily protrude beyond the line AA, which defines on one side, the frame 21 which supports all the members and devices of the module, and has a substantially rectangular shape. Similarly, if the axial plane of electromagnet 13 cooperating with hammer 4, were coincident with the axial plane of said hammer 4, it would protrude beyond line BB. Such protrusion of this electromagnet would fall into corresponding recesses of the adjacent modules, in such a way, as to require overlap mounting which would prevent the removal of a single print module without removing or in some way operating on at least one of the adjacent modules.

To prevent this inconvenience, each hammer of the type having the shape of hammer 1, represented in FIGS. 3a and 3b, is provided, according to the invention, with a deformation in the form of a bending of the arm segment, between the armature and the pivot point of the arm, in a first direction at a first angle and then in a second direction at a second angle to bring the arm into a plane parallel with its initial plane prior to the bending, indicated by P, and each hammer such as hammer 3, represented in FIGS. 4a and 4b, is provided with a similar deformation indicated by P.

As a result of such forming, the axial planes of the armatures 6 and 7 are displaced, in relation to the axial planes of respective extension arms 16 and 19, so that electromagnets such as electromagnets 10 and 13 may be positioned to have their own axial planes mutually coincident, and so as to be confined within the limits of frame 21 of the print module. Therefore, any overlapping of adjacent modules is avoided, and each module may be easily and singularly removed.

The deformation, according to the invention, has another important object. As it has been said before, the motion of the armature, attracted by the electromagnet, is arrested by the polar pieces of the same, before the stroke of the print head 17 is terminated. The remainder of the stroke is accomplished by elastic deformation of the hammer arm.

During this deformation, the deformed portion of said hammer arm is partially submitted to a torsional stress, instead of a bending stress, and therefore provides a precisely limited portion of greater deformability, which provides the greater part of the deformation required to allow the print head 17 to complete its stroke.

Therefore the arm 16 of said hammer behaves substantially as a rigid body and is not subject to uncontrolled high frequency oscillation, as would occur if it were constrained to a bending deformation caused by the sharp stop of the hammer against the polar pieces. Moreover, the impact surface S of head 17, which provides the contact between hammer and typewheel, rotates in a substantially rigid manner about the rotation axis coincident with the axis of axle 5, and therefore its inclination with respect to the typewheel is not subject to variations as might occur due to an elastical bending of arm 16.

Thus, an accurate uniformity of pressure between the head and the typewheel is obtained.

When the printing of a character has been effectuated, the hammer is rapidly brought back not only by reason of the restoring spring 18, but also by reason of the elastic energy stored for the most part by the deformed portion of the hammer arm.

Also in the backward stroke the arm 16 behaves substantially as a rigid body, without oscillating or vibrating at high frequency, thus removing any possibility of rebounds and irregularities in printing.

It should be understood that the foregoing disclosure relates only to a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.

What is claimed is:

1. A hammer module comprising a base plate, a first and second print hammer assembly secured to said base plate, each of said hammer assemblies including an elec tromagnet, an arm carrying a print hammer proximate one extremity thereof and an armature proximate the other extremity thereof and means intermediate said extremities for pivotally securing said arm relative to said electromagnet to provide movement of said print hammer upon attraction of said armature by said electromagnet, each of said arms including a section thereof between said pivot point and said armature wherein the arm extends in one plane, is deformed from said first plane and then reformed to a second plane parallel to said first plane.

2. A hammer module as defined in claim 1 wherein said armatures are disposed in planes substantially at right angles to one another and said print heads are disposed in a parallel spaced apart array.

3. A hammer module comprising a base plate, a first, second, third and fourth print hammer assembly secured to said base plate, each of said hammer assemblies including an electromagnet, an arm carrying a print hammer proximate one extremity thereof and an armature proximate the other extremity thereof and means intermediate said extremities for pivotally securing said arm relative to said electromagnet to provide movement of said print hammer upon attraction of said armature by said electromagnet, each of said arms including a section thereof between said pivot point and said respective armature wherein the arm extends in one plane, is deformed from said first plane and reformed to a second plane parallel to said first plane.

4. A hammer module as defined in claim 1 wherein the first and third armatures are disposed in planes substantially at right angles to said second and fourth armatures and all their respective print hammers are disposed in a parallel spaced apart array.

References Cited UNITED STATES PATENTS 1,537,148 5/1925 Smith 197-143 X 2,940,385 6/1960 House 10193 3,200,739 8/1965 Antonucci 10193 3,266,418 8/1966 Russo 10193 3,314,359 4/1967 Martin 10193 FOREIGN PATENTS 14,882 6/1914 Great Britain.

WILLIAM B. PENN, Primary Examiner US. Cl. X.R. 19735" 

